Method of corrugating cylindrical walls



y 9, 1950 G. J. H. VERMEER 2,507,177

METHOD OF CORRUGATING CYLINDRIGAL WALLS Filed April 12, 1946 GERARD LMN HUBERT US VERMEER INVENTOR.

AGEN 1'.

Patented May 9, 1950 UNITED STATES PATENT OFFICE METHOD OF CORRUGATING CYLINDRI'CAL WALLS Gerard Jan Hube'rtiis Vermeer, Eindhoven, Netherlands, assignor, by mesne assignments, to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application April 12, 1946., Serial No. 661,471 In the Netherlands October 29, 1945 2 Claims;

In certain hot-gas apparatus construction, it is customary to arrange the heater therefor in such manner that ducts for the Working medium as well as ducts for the medium which is in heat-exchanging contact with the working medium are provided in an annular strip present in a section through the said heat-exchanger normal to the axis of the working chamber of the apparatus. In apparatus of this kind the said heater is constituted by a metal zigzag strip. Although this form of construction may be used if for the object in view use is made of a metal strip which is arranged around the working chamber of the engine specially for this purpose and which in its turn is surrounded by the engine wall proper, difficulty arises if the ducts must be provided direct in the wall of the engine, which would be advantageous in View of saving of material.

The present invention provides a solution of this problem.

The hot-gas piston apparatus (a hot-gas piston engine or a refrigerating engine operating according to the reverse hot-gas piston apparatus principle) according to the invention, in which at least one of the heat-exchangers is realized in the above-mentioned manner, has the characteristic that the boundaries of each of the ducts present in the heat-exchanger are formed by the material of the engine Wall at this area which is subdivided into strips by means of longitudinal notches or slots, said strips being alternately bent out of the surface of the engine wall and the gaps thus formed between the edges of each strip and its adjacent strip, which were initially located side by side, being closed by means of plateshaped members. Consequently, in the manufacture of heat-exchangers of this kind at first axial notches or slots are provided in a wall, for example cylindrical in shape, and subsequently at least a certain number of the metal strips thus formed in the wall are bent so as to be located no longer in the planes of the adjacent strips and, finally, the gaps thus formed between the edges of the strips are closed by plate-shaped members, which are fixed in position on th edges of the notches, for example, by a welding or soldering operation.

If, according to one advantageous embodiment of the invention, the notches or slots extend over the cylindical portion of the wall of the engine as well as over a part of the surface of its head, there is the advantage that, owing to the portion of the strip which is derived from the surface of the cylinder head, the strips which are as a hot-gas piston engine.

25 apparatus is designated by 3.

45 combustion gases.

55 strips.

i 2 to be bent out of the surface of the engine wall need not be stretched very much to obtain a reasonable depth of the ducts to be formed, since in this case the depth of the ducts to be formed '5 is substantially dependent on the distance through which the notches extend over the sur# face of the head.

In order that the invention 'may be clearly understood and readily carried into efiect, it will be described more fully by reference to the ac"- companying drawing.

Figure 1 is a view in longitudinal section of the hot portion of a hot-gas piston apparatus according to the invention, which in this case is shown The section is taken along section line l| on Figure 2.

Figure 2 is a plan view of th apparatus shown in Fig. 1.

Figure 3 is a sectional View oi a few ducts present in the heater of the apparatus shown in Figures 1 and 2, the section being taken along section line III-III on Figure 1.

In the form of construction shown, a displacer l is movable in the cylinder 2. The head of the It comprises ducts 4 through which the medium active in the engine is circulating. 5 denotes the ducts in the head through which flow the combustion gases of a burner (not shown), which are in heat-exchanging contact, via the wall of the head, with of the apparatus we consequently find (see Figures 2 and 3) in an annular strip (whose internal and external diameters are indicated in Figure 2 by d1 and d2 respectively) the ducts 4 for the working medium and the ducts 5 for the These ducts are obtained by providing, in parallel with the axis A-A, a certain number of notches or slots of very small width in the head of the apparatus, which initially had the external boundary C-DE-F- GHJ, said notches being provided, for example, by a sawing or milling operation. These notches or slots extend only the lengths ED, GH in the head. By these notches the material of the head \is subdivided into a number of Subsequently, these strips are alternately bent out of the surface of the engine wall, as can be seen from Figure 3, in which the strips 10 and 12 are bent inwardly and the strips II and i3 have retained their initial positions. Owing to the fact that in the construction shown in the drawing the notches extend over the cylindrical portion of the wall of the engine as well as over the surface of its head, the inward bending operation, especially in this form of construction, does not cause any difliculty in view of the fact that the additional length or strip necessary to take care of the portion CK is supplied by the portion of metal bent downwardly from the head portion DE. From Figure 1 it follows that the boundary of a strip bent inwardly extends according to the line CK-- E--F. During the bending operation gaps arise between two edges of one notch, which edges were initially located side by side. In the form of construction shown in Fig. 3 the edge I5 of the strip l3 and the edge I6 of the strip l2 were initially located Side by side. Now, according to the invention, these gaps are closed by means of plate-shaped elements, which may have a substantially rectangular shape and which are denoted by [1, I8, I9, 20 and 2! in Fig. 3. Said elements are connected to the edges of the strips, for example, by a soldering or welding operation. We thus obtain in a simple manner a construction of the head which comprises the ducts required in it for the two media.

As a matter of fact, it is alternatively possible to give the head in its manufacture the external periphery C--KE-F--GLJ, subsequently to provide the notches in it, and then alternately to press the strips thus formed to the exterior. In view of the amounts of material that are to be displaced in bending the strips this is even preferable to the first-mentioned method.

What I claim is:

1. The method of forming a gas passage in the cylinder of a hot gas engine, comprising the steps of forming two adjacent spaced axial slots in a wall portion of said cylinder to form a separated strip, pressing the said strip to a plane displaced from the original plane of the said wall portion to thereby space the edges of said strip from the edges of the adjacent wall portion of said cylinder and covering the spaces thus formed between the strip and the body of the engine cylinder by attaching a plate-shaped member to each of the two edges of the strip and the adjacent edges of the wall portion, respectively.

2. The method of forming a plurality of gas passages in the cylinder of a hot gas engine comprising the steps of forming spaced axial GERARD JAN I-IUBERTUS VERIVIEER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 228,712 Woodbury et a1 June 8, 1880 280,455 Cutler July 3, 1883 1,535,794 Lundgaard Apr. 21, 1925 

